11.22.2012

seven principles of explanatory coherence

paul thagard have been working on a set of principles and computational models of explanatory coherence since late eighties. recently he applied these principles to belief revision about global warming. It helps explain the increasing adoption of the hypothesis that global warming is caused by human activities.

Principle 1. Symmetry. Explanatory coherence is a symmetric relation, unlike, say, conditional probability. That is, two propositions p and q cohere with each other equally.

Principle 2. Explanation. (a) A hypothesis coheres with what it explains, which can either be evidence or another hypothesis; (b) hypotheses that together explain some other proposition cohere with each other; and (c) the more hypotheses it takes to explain something, the lower the degree of coherence.

Principle 3. Analogy. Similar hypotheses that explain similar pieces of evidence
cohere.

Principle 4. Data priority. Propositions that describe the results of observations
have a degree of acceptability on their own.

Principle 5. Contradiction. Contradictory propositions are incoherent with each
other.

Principle 6. Competition. If P and Q both explain a proposition, and if P and Q
are not explanatorily connected, then P and Q are incoherent with each other. (P and Q are explanatorily connected if one explains the other or if together they explain something.)

Principle 7. Acceptance. The acceptability of a proposition in a system of
propositions depends on its coherence with them.